DETERMINATION OF TRACES OF LANTHANIDES IN CERIUM OXIDE BY LIQUID-CHROMATOGRAPHY WITH ON-COLUMN PRECONCENTRATION

Traces of lanthanides can be effectively separated from other lanthanides in major concentrations and other elements by liquid chromatography on a column of Separon SGX C18 silica gel modified by sorption of ammonium dodecylsulphate or ammonium octanesulphonate and determined spectrophotometrically with Arsenazo III. Isocratic or stepwise acidity gradient elution with 90 mmol/l of ammonium 2-hydroxy-2-methylpropionate (HIBA) or 60 mmol/l of ammonium citrate was used. Interferences by the elements up to 10(3)-10(4) concentration ratio can be eliminated. Lanthanides at mg/g level can be determined in cerium oxide with a relative standard deviation s(r) < 2.5% (n = 5).